
α
Alpha, risk of rejecting the null hypothesis erroneously



ANOVA
Analysis of variance

AQL
Acceptable quality level


β
Beta, risk of not rejecting the null hypothesis erroneously

c chart
Control chart for nonconformities

C&E
Cause and effect (diagram)

CL
Center line in an SPC chart

CDF
Cumulative distribution function

Cp
Capability index which shows the process capability potential but does not consider how centered the process is.

Cpk
Capability index used to compare the natural tolerance of a process within the specification limits. Cpk has a value equal to Cp if the process is centered on the nominal; if Cpk is negative, the process mean is outside of the specification limits; if Cpk is between 0 and 1 then the natural tolerances of the process falls outside the spec limits.

COPQ
Cost of poor quality





CUSUM
Control chart which plots the cumulative deviation of each subgroup’s average from the nominal value.



DOE
Design of experiments


DPMO
Defects per million opportunities

FMEA
Failure mode and effects analysis

Gage R&R
Gage repeatability and reproducibility


Ha
Alternative hypothesis

KCA
Knowledge centered activity

KPIV
Key process input variables

KPOV
Key process output variables

LCL
Lower control limit (in SPC)

µ
Mu, population true mean

μ
Estimate of population mean


MSA
Measurement Systems Analysis

MTBF
Mean time between failures


np (chart)
SPC chart of number of nonconforming items

NGT
Nominal group technique


p (chart)
Control chart of the proportion of defective units (or fraction defective) in a subgroup. Based on the binomial distribution

P Value
The probability of making a Type I error.

PDF
Probability density function

ppm
Parts per million (defect rate)

Pp
Performance index (AIAG l995b) (calculated using "longterm" standard deviation)

Ppk
Performance index (AIAG 1995b) (calculated using "longterm" standard deviation)

P/T
Precision to tolerance ratio

QFD
Quality function deployment


RSM
Response surface methodology

RTY
Rolled Throughput Yield

r
Number of failures, correlation coefficient

R2
Coefficient of determination

s
Sigma, population standard deviation

Estimate for population standard deviation

s
Standard deviation of a sample

S Chart
Sample standard deviation chart

SPC
Statistical process control


UCL
Upper control limit (SPC)

u (chart)
SPC chart of number of nonconformities per unit



chart
SPC chart of means (i.e., xbar chart)

Xmr (chart)
SPC chart of individual and moving range measurements

